Induction furnace push-out rod



Jan. 31, 1950 H. A. sTRlcKLAND, JR 2,495,787

r.rNDUcTIoN FuRNAcE PUSH-OUT non Filed Jan. 10, 1946 ATTORNEY HAROLD A. STRICK LANDJR.

itat-nad im. 31,1950 l INDUCTION FURNACE PUSH-OUT ROD Harold A. Strickland, Jr., Detroit, Mich., assignor, by mesne assignments, to The Ohio Crankshaft Company, Cleveland, Ohio, a corporation of Ohio Application January l0, 1946, Serial No. 640,227

(Cl. lli-26) 5 Claims.

This invention relates to apparatus usable in conjunction with furnaces, with particular usability in the conventional coil type of induction furnace wherein the interior of the coil serves as a furnace chamber for the reception and heating of a workpiece. In a furnace of this type, such as shown. for example, in my copending application Serial No. 384,503, filed March 21, 1941, now Patent No. 2,408,350, issued September 24, 1946, there is employed a tubular coil of current-conducting tubing suitably insulated from an interior workpiece-receiving chamber at one end of which is situated a receiving mouthpiece and at the other end of which there is provided a reciprocable rod or the like operable to force the workpiece from its heating position to a point where it may be removed by the workman for subsequent heat treatment. In the use of this rod, which is frequently termed the pusheout rod, because of close association with the workpiece and the ux of the coil. heat is developed in it to such an extent that the end of the same is mushroomed after repeated impacts on the workpiece in its operationof pushing out the workpiece from the heating position. In addition, the tube or stock gage which supports the rod is also flared outwardly because of softening due to heat.

It is one of the main objects of the present invention to provide a push-out rod wherein the tendency to mushroom at the stock gage tip and at the operating tip of the rod is largely obvlated. An additional object of the invention is to provide such a rod which will permit a displacement between the tip and the point where the supporting casing ends so that the heat effect on the casing end will be insuillcient to bring about flaring or other change of the normal form of the same.

An object of the invention is also to provide a push-out rod which is resistant to the impact of the workpiece on being forced into position within the heating chamber of the furnace. Other objects of the invention associated with the specific structure and use will appear on consideration of the embodiment of the invention hereinafter described and illustrated in the accompanying drawings; in which:

Figure 1 is a view of the furnace and associated push-outrod mechanism. partly in sec- 2 tion, illustrating the push-out rod at the limit of its out movement;

Figure 2 is a view of a modication of the pushout rod which also accomplishes the objects of the invention; and

Figure 3 is an end view of the modification of Figure 2.

On making reference to Figure l, it will appear that the base I carries two c-shaped coil-supporting members 2 and 3, each of these members being formed of a c-element 4 adlustably supported on an I-rod 5 and provided with means of vertical adjustment in the screw and nut connection 6. Theupper terminal 'I of the Q-element is apertured to receive the screw-threaded bolt 8 which carries the coil-contact member l with a yieldable connecting spring I0, the member 9 thus being held in yieldable contact against the coil surface oi' its upper side and holding 20 the coil in position against the lower supports only, one of which is shown in the figure.

The furnace coil as shown comprises a squareshaped hollow conductor II wound spirally in tubular form. 'Ihere is provided an outer in- 26 sulation -casing I2 of asbestos-containing furnace insulation material and an inner lining of furnace brick I3 spaced from the conductor by means of sheets of insulation I4, such as mica. Within the iire brick lining and embedded therein are a plurality of rails or liquid-cooled rods I5 which'carry work-support lugs I8 on which the workpiece rests. The workpiece I1 normally nts closely within the chamber I8, just described as formed by the fire brick.

At the inlet end of the furnace a guide metal grill 20 having inwardly curved nngers 2| is provided, there being appropriate attachment to the front casing plate 22 to hold the mouthpiece rigid with reference thereto. The rear wall 2l of the casing supports the push-out mechanism of the furnace construction. There is an aperture formed in the rear casing 2l in alignment with the rear center of the furnace and within this aperture a push-out rod support tube 24 is mounted, the same extending toward the furnace chamber but terminating prior to entry thereof. The tube 24 also extends outwardly from the casing wall whereby thesame may be linearly adjusted through movement in the main support bracket 2i supported by the casing wall.

3 'Ihe shank of the push-out rod l! is supp'ted in this tube 24 and it normally extends inwardly beyond the inner end of the tube into englisment with the workpiece. and outwardly beyond the tubeend. The outer section of the rodear- `ries a stop 26 which is adapted for engagement piece to cause emergence thereof at the mouth-l, piece end, as shown in the outer broken line position of Figure 1. Upon release of the pressure in the reciprocating motor the spring 33 retracts the arm 21 to permit movement of the push-out rod on placement of a new load in the furnace chamber. The push-out rod Il is positioned along the axis of the chamber coil Il and has a diameter in relation to the coil reduced less than that of eillcient coupling for the coil frequency and current at heating values. the rod diameter in the contact section Il preferably being less than one-third of the, inner diameter of the heating coil. Thus the possibility oi heating due to flux flow is substantially diminished. This is true from the mere fact that the ilux density is largely dependent upon the size of the conductor within the chamber tube in relation to the size of the chamber. Hence in the time interval of heat treatment the heating of the rod in opposition to the normal rate of radiation and cooling conduction is lessened to a point where no deleterious results occur. Accordingly, by this construction the inner end of the tip, as well as the inner end of the support tube, maintains its original shape during a heating cycle or a series of heating cycles and mushroom formations are avoided.

In Figure 2 I have shown a modiilcation of the invention in which the tip head of the pushout rod is enlarged in diameter to that of the support tube. In this form of the invention the tube 24 supporting the push-out rod I! is similar to that of the modification of Figure 1. The head has a diameter uniform throughout its length except at the extreme end of tip 4l which is somewhat constricted as shown, the base element 42 having a diameter the same as the diameter of the supporting tubing 24.

In making the engagement head 4I preference is given to the form as shown in Figure 3 obtained by placement of a short tube on the inner end of the push-out rod Il. This is closely fitted and attached so as to form a permanent engagement with the push-out rod. Formed in the tubing or shell and in the body of the push-out rod itself are a plurality of grooves 43 which extend-'in alignment with the axis of the pushout rod from a point near the extreme outer surface of the base section 42 to the inner end of the shell and push-out rod` The purpose of these grooves is to destroyl the continuity of circuital currents formed in the head of the push-out rod by furnace magnetic flux. thereby maintaining heating effect on the push-out'rod and the engagement head below the danger point where fusion of the head tip or ofthe support tube tip may result.

In either modification the stop. as collar 31,

4 isplacedadiaeentthecoilendofsupporttube 24. However, in some structures it is desirable that the stop be formed on the external side of the support tube. 5 While I have indicated two preferred forms of my invention. the apparatus lends itself to additional modification, and hence no limitation is implied by the selected description other than may be required by the scope of the claims hereto appended.

What is claimed is:

l. A push-out mechanism particularly adapted for electric induction furnaces and the like comprising a support, a rod shank axially movable on said support, means for moving said shank. and a head at one end of the shank having a first section adjacentA the shank larger in diameter than the shank forming a stop against said support and a second section adjacent the head end of lesser diameter than the first section and adapted at least at times to be within the infi'uence of the magnetic field of said furnace, said second section having a length substantially in excess of the first section.

2. A push-out mechanism particularly adapted for electric induction furnaces'and the like coinprising a support, a rod shank axially movable on said support, meansl for moving said shank, and a head at one end of the shank having a diameter in excess of that of tie shank, said head adapted at least at times to be within the influence of the magnetic field of said furnace and having axial surface slots formed therein for reduction of eddy current ilow.

3. A pushout mechanism particularly adapted for electric induction furnaces and the like comprising a support, a rod shank axially movable on said support, means for moving said shank, and a head at one end of 'the shank having a first section adiacent the shank larger in diameter than the shank forming a stop against said support and a second section in extension from said first section formed as an elongated contact element for engagement with the work- 45 piece and said second section adapted at least at times to be within the magnetic field of said furnace, at least portions of said second section having a diameter substantially less than said first section, whereby the heating of said second section as 'a result of induced currents is held to a minimum.

4. In induction furnace construction, a base.

an induction heating coil mounted on said base,

a support mounted un said base at one end of said coil, a tube vmounted on said support to lie along the axis of said coil with the coil-adjacent end displaced outwardly from the coil end, and

a rod slidably supported in said tube, said rod having an enlarged stop section engageable with the tube and adi acent the coil to limit movement of the rod away from "said coil, and an end section having a diameter less than one-third the inner diameter of the coil whereby induced currents in said end section are held to a minimum, the end section of the rod being adapted to engage a workpiece.

5. In induction furnace construction, a base,

an induction heating coil mounted on said base,

a support mounted on said base at one end of said coil, a tube mounted on said support to lie along the axis of said coil with the coil-adjacent end displaced outwardly from the coil end, and a rod slidably supported in said tube, said rod having a workpiece engaging end section of a diameter leas than one-third the inner dimmmmmmwmmw Mmmmmmmm? .jlm .zz E mn 6 mmnvmmmh. Mweunnn Hmm hmmm mu ummm mmgm Qmmmmmmmmmmwumm N LLLIL22'22. I m. .m NAW mm mm mm mm m @am mm n z Ss smv. a mw www E ZM C g mmm d mmurmu mm ne mi. an m NM 

